drm/amdgpu: SRIOV flr_work should take write_lock

[Why]
If flr_work takes read_lock, then other threads who takes
read_lock can access hardware when host is doing vf flr.

[How]
flr_work should take write_lock to avoid this case.
Signed-off-by: Jingwen Chen <Jingwen.Chen2@amd.com>
Reviewed-by: Monk Liu <monk.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c

@@ -252,7 +252,7 @@ static void xgpu_ai_mailbox_flr_work(struct work_struct *work)
 	 * otherwise the mailbox msg will be ruined/reseted by
 	 * the VF FLR.
 	 */
-	if (!down_read_trylock(&adev->reset_sem))
+	if (!down_write_trylock(&adev->reset_sem))
 		return;
 
 	amdgpu_virt_fini_data_exchange(adev);
@@ -268,7 +268,7 @@ static void xgpu_ai_mailbox_flr_work(struct work_struct *work)
 
 flr_done:
 	atomic_set(&adev->in_gpu_reset, 0);
-	up_read(&adev->reset_sem);
+	up_write(&adev->reset_sem);
 
 	/* Trigger recovery for world switch failure if no TDR */
 	if (amdgpu_device_should_recover_gpu(adev)

drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c

@@ -273,7 +273,7 @@ static void xgpu_nv_mailbox_flr_work(struct work_struct *work)
 	 * otherwise the mailbox msg will be ruined/reseted by
 	 * the VF FLR.
 	 */
-	if (!down_read_trylock(&adev->reset_sem))
+	if (!down_write_trylock(&adev->reset_sem))
 		return;
 
 	amdgpu_virt_fini_data_exchange(adev);
@@ -289,7 +289,7 @@ static void xgpu_nv_mailbox_flr_work(struct work_struct *work)
 
 flr_done:
 	atomic_set(&adev->in_gpu_reset, 0);
-	up_read(&adev->reset_sem);
+	up_write(&adev->reset_sem);
 
 	/* Trigger recovery for world switch failure if no TDR */
 	if (amdgpu_device_should_recover_gpu(adev)